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Metal‐organic frameworks (MOFs) have been extensively studied and applied as promising active materials in the field of energy storage and conversion. Recently, conductive π‐d conjugated coordination polymers (CCPs) have garnered significant attention due to their high conductivity, high porosity, tunable components, and adjustable pore sizes. These CCPs typically consist of transition metal ions and organic ligands, forming an in‐plane π‐d conjugated system. In this review, a concise summary of the design principles are provided, synthesis methods, and reaction mechanisms of CCPs as electrodes for energy storage systems, including metal‐ion batteries and supercapacitors. In addition, several novel energy storage applications are highlighted, such as metal‐air batteries and photo‐enhanced batteries. Finally, the challenges that need to be addressed is discussed urgently and offer perspectives on the further application of CCPs in more advanced energy storage and conversion systems. [ABSTRACT FROM AUTHOR]

The introduction of an electrocatalyst to accelerate the kinetics of lithium polysulfides (LiPSs) reduction/oxidation is beneficial to enhance the capacity of sulfur cathode and inhibit the shuttling effect of LiPSs. However, current electrocatalysts mainly focus on the metal‐based active sites to reduce the reaction barriers, and there remains a great challenge in developing light‐weighted metal‐free catalysts. In this work, 1D graphitic carbon nitride nanorods (g‐C3N4‐NRs) with carboxyl (─COOH) and acylamide (─CONH2) functional groups are designed as metal‐free electrocatalysts for lithium‐sulfur batteries to accelerate the transport of Li+ and the conversion of LiPSs. The density functional theory (DFT) calculations prove that the existence of ─COOH group realizes the adsorption of LiPSs and accelerates the transport of Li+, while the ─CONH2 groups reduce the reaction energy barrier of S8 to Li2S. In addition, in situ UV–vis and Li2S nucleation/dissociation experiments also verify that g‐C3N4‐NRs achieve rapid adsorption and transformation of LiPSs under the synergistic action of ─COOH and ─CONH2 functional groups. Consequently, the sulfur cathode based on the g‐C3N4‐NRs‐PP separator remains at a specific capacity of 700.3 mAh g−1 after 70 cycles at 0.2 C, at 0 °C. This work provides a new strategy for breaking through the bottleneck of metal‐free catalysts for high‐performance lithium‐sulfur batteries. [ABSTRACT FROM AUTHOR]

Among various energy storage devices, lithium-sulfur batteries are the most promising candidate due to their high energy density and low cost. Polysulfide migration is a severe problem to inhibit the wide application of lithium-sulfur batteries. The efficient polysulfide inhibition is a determining factor for the high electrochemical performance of lithium-sulfur batteries. Therefore, the development of suitable host materials can inhibit that polysulfide inhibition has become a hot topic of research. Herein, we propose that the C/MoS2 composites can be used as sulfur host to catalyze the polysulfide conversion to improve the cycle stability of lithium-sulfur batteries. Thanks to the presence of the C/MoS2 host, the as-prepared C/MoS2@S cathode exhibits high capacity even at high rate of 5 C. This work provides direct evidence for the catalytic effect of C/MoS2 for accelerating polysulfide conversion kinetics. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur battery (LSB) chemistry is regarded as one of the most promising contenders for powering next‐generation electronics, including electric vehicles. This is due to its high theoretical capacity, the use of inexpensive and environmentally friendly materials, and its alignment with climate‐smart manufacturing principles. Sulfur, the electroactive element in LSBs, undergoes lithiation to form a series of polysulfides, each contributing to the battery's energy density. However, this chemistry encounters several challenges, particularly concerning the stability of sulfur. Recent studies have shown that the presence of a full gamma phase of sulfur in an LSB cathode significantly enhances the capacity and overall cell performance. However, despite the advantages of cathodes with gamma sulfur, the characteristics of LSBs with mixed crystal phases of sulfur (alpha, beta, and gamma) have not been extensively studied. In this context, we developed a simple and cost‐effective synthesis method to produce both single‐phase (alpha) and mixed‐phase sulfur (primarily a mixture of alpha and gamma, with a trace of beta) and conducted their detailed physical and electrochemical characterization for use as electroactive cathode materials in LSBs. The cells fabricated using sulfur‐carbon black as the cathode delivered a specific capacity of approximately 640 mAh/g at a current density of 275 mA/g, demonstrating excellent cyclic stability over 50 cycles with a capacity retention of around 97%. This performance is superior to that of the sulfur‐baked carbon black composite cathode, which achieved 440 mAh/g at the same current density. [ABSTRACT FROM AUTHOR]

MXenes are promising passive components that enable lithium‐sulfur batteries (LSBs) by effectively trapping lithium polysulfides (LiPSs) and facilitating surface‐mediated redox reactions. Despite numerous studies highlighting the potential of MXenes in LSBs, there are no systematic studies of MXenes' composition influence on polysulfide adsorption, which is foundational to their applications in LSB. Here, a comprehensive investigation of LiPS adsorption on seven MXenes with varying chemistries (Ti2CTx, Ti3C2Tx, Ti3CNTx, Mo2TiC2Tx, V2CTx, Nb2CTx, and Nb4C3Tx), utilizing optical and analytical spectroscopic methods is performed. This work reports on the influence of polysulfide concentration, interaction time, and MXenes' chemistry (transition metal layer, carbide and carbonitride inner layer, surface terminations and structure) on the amount of adsorbed LiPSs and the adsorption mechanism. These findings reveal the formation of insoluble thiosulfate and polythionate complex species on the surfaces of all tested MXenes. Furthermore, the selective adsorption of lithium and sulfur, and the extent of conversion of the adsorbed species on MXenes varied based on their chemistry. For instance, Ti2CTx exhibits a strong tendency to adsorb lithium ions, while Mo2TiC2Tx is effective in trapping sulfur by forming long‐chain polythionates. The latter demonstrates a significant conversion of intermediate polysulfides into low‐order species. This study offers valuable guidance for the informed selection of MXenes in various functional components benefiting the future development of high‐performance LSBs. [ABSTRACT FROM AUTHOR]

An artificial solid electrolyte interphase (SEI) with lithiophilic sites and chemical bonds anchoring lithium polysulfides (LiPSs) has been developed as a potential solution to protect the lithium (Li) metal anode of Lithium−sulfur (Li–S) batteries. This strategy aims to guide consistent Li deposition and relieve lithium corrosion. Herein, the evolution process of lithiophilic sites based on aluminum fluoride (AlF3) in an artificial SEI is disclosed in Li–S batteries with metal−based lithiophilic sites. The polyester polymer (PMMA and PPC)/AlF3 artificial SEI (MPAF−SEI) was homogeneously anchored on Li anode by in−situ polymerization. The conversion of AlF3 into Li–Al and LiF lithiophilic sites effectively reduce the Li nucleation overpotential and prevents the formation of Li dendrites. At the same time, the polymer can anchor LiPSs by chemical bonds and prevents Li corrosion. The optimized MPAF−SEI protected Li demonstrates excellent stability for over 3000 h at a capacity of 1 mAh cm−2 in Li || Li symmetric cells. The Li–S battery with low N/P (4) exhibits a capacity of 532.6 mAh g −1 over 300 cycles lifespan at 0.5 C.

[Display omitted] • We develop NiCo alloy-decorated nitrogen-doped carbon double-shelled hollow polyhedrons (NC/NiCo DSHPs) as highly efficient catalysts for Li-S batteries. • The distribution of NiCo alloy on both the inner and outer shells ensures sufficient catalytic active sites, which can effective adsorb LiPSs and mitigate the shuttle effect, even at high loadings, and facilitate the conversion between LiPSs and Li 2 S, enabling enhanced redox kinetics of Li-S systems. • Benefiting from the advantages of composition and structure, Li-S batteries, using porous NC/NiCo DSHPs as separator coating material, achieve a high specific capacity of 1310 mAh g-1 at 0.2 C, a superior cycling performance with low capacity fading of 0.045% per cycle at 1 C after 800 cycles. Lithium-sulfur (Li-S) batteries have received significant attention due to their high theoretical energy density. However, the inherent poor conductivity of S and lithium sulfide (Li 2 S), coupled with the detrimental shuttle effect induced by lithium polysulfides (LiPSs), impedes their commercialization. In this study, we develop NiCo alloy-decorated nitrogen-doped carbon double-shelled hollow polyhedrons (NC/NiCo DSHPs) as highly efficient catalysts for Li-S batteries. The distribution of NiCo alloy on both the inner and outer shells provides abundant catalytic active sites, effectively adsorbing LiPSs, mitigating the shuttle effect, and promoting the conversion between LiPSs and Li 2 S, even at high sulfur loadings. This results in enhanced redox kinetics within the Li-S system. Moreover, the highly conductive carbon material framework, enriched with carbon nanotubes and graphitic carbon layers, can greatly promote the efficient electron transportation. Additionally, the improved ion diffusion rates benefiting from the hollow structure can also be realized. By harnessing these synergistic effects, Li-S batteries incorporating the double-shelled NC/NiCo DSHP catalysts achieved a high specific capacity of 1310 mAh/g at 0.2C and a superior rate performance of 621 mAh/g at 4C. Furthermore, excellent cycling performance with ultralow capacity fading rate of only 0.045 % per cycle after 800 cycles at 1C was achieved. When sulfur loading reaches 6 mg cm−2, a high capacity of 4.6 mAh cm−2 at 0.1C after 100 cycles further validates the practical potential of this design. This study presents an innovative approach to alloy catalyst design, offering valuable insights for future research of Li-S batteries. [ABSTRACT FROM AUTHOR]

Low rate activation process is always used in conventional transition metal oxide cathode and fully activates active substances/electrolyte to achieve stable electrochemical performance. However, the related working mechanism in lithium‐sulfur (Li‐ battery is unclear due to the multiple complex chemical reaction steps including the redox of sulfur and the dissolution of polysulfides intermediate. Hence, the influencing mechanism of activation process on Li‐S battery is explored by adopting different current densities of 0.05, 0.2, and 1 C in initial three cycles before long‐term cycling tests at 0.2 C (denoted by 0.05, 0.2, and 1‐battery). 0.05‐battery presents the highest initial capacity in activation process, while 0.2‐battery presents superior electrochemical performances after 150 cycles. The similar trend can be found in more long‐term cycling rates such as 0.02, 0.1, 0.5, and 1 C. Potentiostatically Li2S precipitation test demonstrates that rapid generation of Li2S is achieved at higher current density, and S8‐Li2Sn‐Li2S conversion is accelerated according to Tafel plots. However, interfacial electrochemical and physical characterizations suggest that serious lithium dendrite growth will be induced under high current density. Therefore, considering the reaction kinetics and interfacial properties, low rate activation process is unnecessary when cycling current lower than 1 C for Li‐S battery. [ABSTRACT FROM AUTHOR]

The failure of lithium‐sulfur (Li‐S) batteries operating under lean‐ether‐electrolyte conditions can be ascribed to the deterioration of electrolytes, the passivation of cathodes, and the degeneration of lithium anodes. Efforts to address these challenges by exploring alternative electrolytes beyond commonly used ether‐based systems often introduce new complications. In this study, the utilization of a multifunctional additive, 2‐Bromoacetamide (BA), for ether electrolytes is proposed to achieve stable Li‐S batteries under lean‐electrolyte conditions. These investigations reveal that the amide bond in BA forms hydrogen bonds with sulfur atoms, promoting the dissolution of lithium sulfides (Li2S) in ether electrolytes and mediating the conversion of lithium polysulfides. This enhanced solubility of Li2S facilitates 3D deposition (vertical to the substrate) rather than the typical 2D deposition (parallel to the substrate) of Li2S, and thus alleviates the passivation of cathodes. Furthermore, the incorporation of BA promotes uniform and dense lithium deposition. The use of the BA‐containing electrolyte enables stable cycling of a Li‐S pouch cell for 40 cycles, even under a low electrolyte‐to‐sulfur ratio of 4 µL mg−1. This multifunctional strategy offers an effective solution to extend the lifetime of Li‐S batteries under lean‐electrolyte conditions, thereby paving the way for practical applications of Li‐S battery technology. [ABSTRACT FROM AUTHOR]

Theoretically, lithium–sulfur (Li‐S) batteries are highly promising candidates for renewable energy applications, given their scalable energy density and low cost. However, their current practical performance is limited below theoretical expectations, despite attempts to accommodate volumetric expansion and improve electrical conductivity with porous S‐anchoring supports. Battery performance is primarily rate‐limited by the sluggish redox and conversion reaction kinetics of lithium polysulfides (LiPS), which respectively transform into lithium sulfide (Li2S) and elemental S through charging and discharging galvanostatic cycles. Given their strong electrocatalytic performance and other pertinent benefits, recent research highlights single‐atom catalysts (SACs) as candidates for enhancing Li‐S batteries. Thus, this review summarizes contemporary advancements regarding SAC implementation in Li‐S batteries, primarily emphasizing catalyst morphology, battery performance, and mechanistic elucidation. More specifically, separators and cathodes can be engineered via SACs to better anchor LiPS and improve their reductive kinetics, thereby inhibiting the "shuttle effect" known to impact Li‐S batteries. In addition, SACs can be modulated with functional groups to synergistically improve performance, enabling higher S loadings and redistributing transferred charge. Overall, SACs conspicuously boost Li‐S battery performance, justifying further research toward their implementation in Li‐S batteries. [ABSTRACT FROM AUTHOR]

Phase engineering is considered an effective strategy to regulate the electrocatalytic activity of catalysts for Li–S batteries (LSBs). However, the underlying origin of phase‐dependent catalytic ability remains to be determined, which significantly impedes the design principles of high‐performance catalytic materials for LSBs. Herein, heteroatom‐doped engineering can trigger phase transformation from mixed‐phased cubic and orthorhombic cobalt diselenide into pure orthorhombic structure with a tensile strain and enhanced charge localization. The upshift of the d‐band center and enhanced Bader charge at Se sites synergistically strengthen the interaction with Li and S sites in polysulfide species, thus endowing the transformed P‐MoSe2/MXene with high catalytic activity and uniform lithium deposition for LSBs. Consequently, the P‐CoSe2/MXene Li–S batteries demonstrate a high‐rate capability of 603 mAh g−1 at 4C, and an excellent cyclability of 652 mAh g−1 at 1C over 500 cycles with a degradation rate of 0.076% per cycle. The work provides an in‐depth insight into the fundamental design principles of effective catalysts for LSBs. [ABSTRACT FROM AUTHOR]

[Display omitted] The application of Li-S batteries on large scale is held back by the sluggish sulfur kinetics and low synthesis efficiency of sulfur host. In addition, the preparation of catalysts that promote polysulfide redox kinetics is complex and time-consuming, reducing the cost of raw materials in Li-S. Here, a universal synthetic strategy for rapid fabrication of sulfur cathode and metal compounds nanocatalysts is reported based on microwave heating of graphene. Heat-sensitive materials can achieve rapid heating due to graphene reaching 500 ℃ within 4 s via microwave irradiation. The MoP-MoS 2 /rGO catalyst demonstrated in this work was synthesized within 60 s. When used for catalysts for Li-S batteries whose graphene/sulfur cathodes were also synthesized by microwave heating, enhanced catalytic effect for sulfur redox reaction was verified via experimental and DFT theoretical results. Benefiting from fast redox reaction (MoP), smooth Li+ diffusion pathways (MoS 2), and large conductive network (rGO), the assembled Li-S battery with MoP-MoS 2 /rGO-Add@CS displays a remarkable initial specific capacity, stable lithium anode and good cycle stability (in pouch cells) using this two-pronged strategy. The work provides a practical strategy for advanced Li-S batteries toward a wide range of applications. [ABSTRACT FROM AUTHOR]

The performance of Lithium–sulfur (Li–S) batteries is constrained by the migration of lithium polysulfide (LiPS), the slow conversion of LiPS, and the significant reaction barrier encountered during the precipitation/dissolution of Li2S throughout the discharge/charge cycle. In this contribution, the study presents Ni–Co dual‐atom catalytic sites on hollow nitrogen‐doped carbon (NiCoNC). Theoretical calculations and experimental data reveal that the dual‐atom catalysts (DACs) accelerate the kinetic conversion of LiPSs and facilitate the formation/decomposition of Li2S during discharging and charging, which minimizes LiPS migration. Consequently, the utilization of S/NiCoNC cathodes manifests a substantial initial capacity of 1348.5 mAh g−1 at 0.1 C, exceptional cycling stability with an average capacity degradation rate of 0.028% per cycle over 900 cycles at 0.5 C, and noteworthy rate capability with a capacity of 626 mAh g−1 at 2 C. Electrodes with a higher sulfur loading of 4.5 mg cm−2 and a low electrolyte/sulfur ratio of 8 µL mg−1 exhibit exceptional specific capacities of up to 1236 mAh g−1 at 0.1 C, as well as noteworthy capacity retention of 494.2 mAh g−1 after 200 cycles at 0.2 C. This study effectively showcases the potential of DACs as catalysts for sulfur cathodes, thereby enhancing the overall performance of Li–S batteries. [ABSTRACT FROM AUTHOR]

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Despite the very high theoretical energy density, Li‐S batteries still need to fundamentally overcome the sluggish redox kinetics of lithium polysulfides (LiPSs) and low sulfur utilization that limit the practical applications. Here, highly active and stable cathode, nitrogen‐doped porous carbon nanotubes (NPCTs) decorated with NixCo1‐xS2 nanocrystals are systematically synthesized as multi‐functional electrocatalytic materials. The nitrogen‐doped carbon matrix can contribute to the adsorption of LiPSs on heteroatom active sites with buffering space. Also, both experimental and computation‐based theoretical analyses validate the electrocatalytic principles of co‐operational facilitated redox reaction dominated by covalent‐site‐dependent mechanism; the favorable adsorption‐interaction and electrocatalytic conversion of LiPSs take place subsequently by weakening sulfur‐bond strength on the catalytic NiOh2+−S−CoOh2+ backbones via octahedral TM‐S (TM = Ni, Co) covalency‐relationship, demonstrating that fine tuning of CoOh2+ sites by NiOh2+ substitution effectively modulates the binding energies of LiPSs on the NixCo1‐xS2@NPCTs surface. Noteworthy, the Ni0.261Co0.739S2@NPCTs catalyst shows great cyclic stability with a capacity of up to 511 mAh g−1 and only 0.055% decay per cycle at 5.0 C during 1000 cycles together with a high areal capacity of 2.20 mAh cm−2 under 4.61 mg cm−2 sulfur loading even after 200 cycles at 0.2 C. This strategy highlights a new perspective for achieving high‐energy‐density Li‐S batteries. [ABSTRACT FROM AUTHOR]

Metal phosphides fabricated using metal organic frameworks (MOF) have recently been widely studied in lithium-sulfur (Li–S) battery because of the unique microstructure and electrocatalytic activity. However, the growth of MOF is very rapid and the particle size mainly focuses on micrometer, which severely limits the catalytic effect. Herein, we fabricate nanoscale MOF embedded with carbon nanotube (CNT), owing to the ultra-small CoP (25 nm, denoted as S-CoP) derived from the phosphating of MOF and unique network of CNT, the designed micro-nano structure S-CoP/CNT accelerates the conversion of lithium polysulfides (LiPSs), boosts the precipitation/decomposition processes of lithium sulfide (Li2S) and provides an effective adsorption barrier. Meanwhile, the fabricated S-CoP/CNT separator endows an ultralong dendrite-free Li deposition up to 1714 h. The Li–S battery with S-CoP/CNT modified separator can deliver an initial capacity of 1513.22 mAh g−1 at 0.1 °C, a reversibility capacity of 574.95 mAh g−1 up to 500 cycles at 0.5 °C. The satisfactory performance is also verified at a high sulfur loading of 4.2 mg cm−2 and a favorable initial capacity of 1161.8 mAh g−1 can be maintained. This study provides a facile strategy to fabricate nano metal phosphides derived from MOF for Li–S battery. [ABSTRACT FROM AUTHOR]

Mesoporous metal oxide nanosheets (MMONs) are demonstrated great promise for various catalytic applications such as water splitting, CO2 reduction, and metal–sulfur batteries. However, limited by the conventional high‐temperature synthetic routes, the prepared MMONs expose only a small portion of the effective catalytic sites, which greatly restricts their electrocatalytic activity. Herein, a facile and general glycine‐assisted strategy is developed to synthesize a series of MMONs with high crystallinity and remarkable porosity. Impressively, single‐phase perovskite type MMONs containing up to ten metal cations can be synthesized easily using this method without any further purification step. As a proof of concept, the Li–S cell with mesoporous LaFe0.4Co0.2Ni0.2Cu0.2O3 nanosheets as catalyst achieves superior ultralong cycling life over 1500 cycles at 2 C with only 0.041% capacity decay per cycle and a high areal capacity reaching 6.0 mAh cm−2 at a low electrolyte/sulfur ratio of 5.9 µL mg−1. The improved performance is attributed to abundant active sites and synergistic contribution of multicomponent. This work paves a new avenue for the general synthesis of advanced MMONs and will inspire the practical applications in different fields. [ABSTRACT FROM AUTHOR]

A significant advancement in materials science has been made with the 2D MXene nanomaterials that were etched from their parent 3D MAX phases. Layered ternary carbide, nitride, and boride compounds with the general formula Mn+1AXn (n=1,2, 3,4 ...) make up the 3D MAX phase materials, where A is an element of Group IIA or IIIA, M is an early transition metal, and X is either C, N, or B. MXene's chemical formula is Mn+1Xn, whereas that of the precursor is Mn+1AXn. The MAX materials have a distinct set of properties that are similar to those of metal and ceramic. They are helpful in the development of high-efficiency engines, thermal systems that can withstand damage, fatigue resistance enhancement, and high-temperature rigidity retention technologies. The 2D MXenes are potentially described as a „wonder material‟ in the class of nanomaterials. Because of their intriguing mechanical properties resulting from their atomically thin dimensions, as well as their unusual electrical and optical properties, these have become the focus of materials research in recent years. These nanomaterials are multilayer electrically conductive materials that are comparable to multilayer graphene. They have been discovered to be beneficial for a variety of applications, such as energy storage materials, composite reinforcement, chemical, environmental, and biological sensors, and electronic devices. The recent advancements in the use of nanomaterials in optoelectronics, field-effect transistors, transparent conductive electrodes and shielding against electromagnetic interference, energy storage, and other fields have been extensively documented. The potential of nanomaterials as a novel ceramic photothermal agent employed in cancer therapy has been revealed by a very recent study on Ti3C2 MXene. The same 2D nanomaterial can be used in water desalination and purification membranes since it has antibacterial qualities and is resistant to bio fouling. The MXene-based piezoresistive sensor is also capable of detecting weak pressures and the slight bending-release actions of humans. It can be applied to recover lost frictional energy from, say, walking or typing-related muscular contractions. Since MAX phases are precursors to MXenes, the former are valuable due to the growing interest in the latter. This review provides an overview of the literature, including the author's own work, from the groundbreaking MXene publication to the present. It provides information on the characteristics, synthesis, crystal structure, and current and future uses of the new wonder materials as well as the MAX phases. [ABSTRACT FROM AUTHOR]

A catalytic pseudo-8-electron redox reaction of sulfur is achieved by facilitating the disproportionation of high-order polysulfide ions in a Li-Sulfur battery. Electrochemically generated polysulfide ions (Sx2-, where 3

Abstract Despite the very high theoretical energy density, Li‐S batteries still need to fundamentally overcome the sluggish redox kinetics of lithium polysulfides (LiPSs) and low sulfur utilization that limit the practical applications. Here, highly active and stable cathode, nitrogen‐doped porous carbon nanotubes (NPCTs) decorated with NixCo1‐xS2 nanocrystals are systematically synthesized as multi‐functional electrocatalytic materials. The nitrogen‐doped carbon matrix can contribute to the adsorption of LiPSs on heteroatom active sites with buffering space. Also, both experimental and computation‐based theoretical analyses validate the electrocatalytic principles of co‐operational facilitated redox reaction dominated by covalent‐site‐dependent mechanism; the favorable adsorption‐interaction and electrocatalytic conversion of LiPSs take place subsequently by weakening sulfur‐bond strength on the catalytic NiOh2+−S−CoOh2+ backbones via octahedral TM‐S (TM = Ni, Co) covalency‐relationship, demonstrating that fine tuning of CoOh2+ sites by NiOh2+ substitution effectively modulates the binding energies of LiPSs on the NixCo1‐xS2@NPCTs surface. Noteworthy, the Ni0.261Co0.739S2@NPCTs catalyst shows great cyclic stability with a capacity of up to 511 mAh g−1 and only 0.055% decay per cycle at 5.0 C during 1000 cycles together with a high areal capacity of 2.20 mAh cm−2 under 4.61 mg cm−2 sulfur loading even after 200 cycles at 0.2 C. This strategy highlights a new perspective for achieving high‐energy‐density Li‐S batteries.

Li‐S batteries possess high energy density and have been one of the most promising energy storage systems. For sulfur cathodes, the electrochemical performance is still seriously hindered by the polysulfide shuttling and sluggish conversion kinetics. It has been demonstrated to be one effective strategy to address the above issues via designing electrocatalysts with robust affinity and catalytic capacity towards polysulfides. However, it is still a great challenge to rapidly and economically discover high‐performance electrocatalysts. Herein, using density functional theory calculation, we studied the chemisorption‐catalysis behavior of sulfur species on a series of electrocatalysts (MCo2X4, M=Co, Zn, Cu, Ni, Fe, and Mn, X=O, S, and Se) to assess the effect of the anions and cations co‐regulation on their electronic structure, chemisorption behavior, and catalytic property. FeCo2Se4 and CuCo2Se4 combined appropriate chemisorption with superior electronic conductivity and sulfur reduction catalytic capacity have been predicted as novel electrocatalysts for high‐performance Li‐S batteries. This study gives theoretical guidance for rapid discovery of high‐efficient electrocatalyst to boost the electrochemical performance of sulfur cathodes. [ABSTRACT FROM AUTHOR]

Introducing strain is considered an effective strategy to enhance the catalytic activity of host material in lithium‐sulfur batteries (LSB). However, the introduction of strain through chemical methods often inevitably leads to changes in chemical composition and phase structure, making it difficult to truly reveal the essence and root cause of catalytic activity enhancement. In this paper, strain into MoS2 is introduced through a simple heat treatment and quenching. Experimental research and theoretical analysis show that the strain raises parts of antibonding orbitals in Mo─S bonds above the Fermi level and weakens Li─S and S─S bonds, resulting in tight anchoring and accelerating the conversion for lithium polysulfides (LiPSs). The cells based on the MoS2 with high strain delivers an initial discharge specific capacity as high as 1265 mAh g−1 under 0.2 C and a low average capacity fading of 0.041% per cycle during 1500 cycles under 1 C. This research work deeply reveals the origin of strain effects in the reaction process of LSB, providing important design principles and references for the rational design of high‐performance catalytic materials in the future. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries offer the potential for significantly higher energy density and cost-effectiveness. However, their progress has been hindered by challenges such as the "shuttle effect" caused by lithium polysulfides and the volume expansion of sulfur during the lithiation process. These limitations have impeded the widespread adoption of lithium–sulfur batteries in various applications. It is urgent to explore the high-performance sulfur host to improve the electrochemical performance of the sulfur electrode. Herein, bimetallic NiFe hydroxide (NiFe-LDH)-modified carbon nanotubes (CNTs) are prepared as the sulfur host materials (NiFe-CNT@S) for loading of sulfur. On the one hand, the crosslinked CNTs can increase the electron conductivity of the sulfur host as well as disperse NiFe-LDHs nanosheets. On the other hand, NiFe-LDHs command the capability of strongly adsorbing lithium polysulfides and also accelerate their conversion, which effectively suppresses the shuttle effect problem in lithium polysulfides. Hence, the electrochemical properties of NiFe-CNT@S exhibit significant enhancements when compared with those of the sulfur-supported pure NiFe-LDHs (NiFe-LDH@S). The initial capacity of NiFe-CNT@S is reported to be 1010 mAh g−1. This value represents the maximum amount of charge that the material can store per gram when it is first synthesized or used in a battery. After undergoing 500 cycles at a rate of 2 C (1 C = 1675 mA g−1), the NiFe-CNT@S composite demonstrates a sustained capacity of 876 mAh g−1. Capacity retention is a measure of how well a battery or electrode material can maintain its capacity over repeated charge–discharge cycles, and a higher retention percentage indicates better durability and stability of the material. [ABSTRACT FROM AUTHOR]

The combination and structural regulation of physical adsorption and chemisorption carriers for polysulfides play an important role in limiting the shuttle effect of lithium-sulfur batteries (LSBs). So, in this paper, N, Co co-doped moss-like porous biochar (Co–N/CWPC) is synthesized and used as the sulfur host for LSBs. A large number of pores in the "moss" provide space for sulfur storage and volume expansion. And the introduction of N, Co provides plentiful catalytic adsorption sites, which can not only effectively limit the shuttle of polysulfides but also accelerate the conversion rate of polysulfides to the final discharge products. Moreover, Co also promotes graphitization and improves electrical conductivity of the biochar. After sulfur injection, the electrode shows an initial capacity of 787 mAh g−1 at 0.5 C and maintaining a capacity of 500 mAh g−1 after 500 cycles, the capacity decay rate is 0.07%. Even at a discharge rate of 1.0 C, it still maintained a capacity of 373 mAh g−1 after 1000 revolutions, with a capacity decay rate of 0.04%. [ABSTRACT FROM AUTHOR]

δ‐Manganese dioxide (δ‐MnO2) is a 2D material which possesses distinct properties and features due to its unique atomic structure and has already been utilized in numerous disciplines recently, especially in the field of magnetism, energy storage, magnetic resonance imaging, biocatalysts, and fluorescence sensing. Keeping an eye on the huge potential of this 2D material, we report our recent discovery of single‐step synthesis of MnO2 nanosheets via bottom‐up laser crystallization (of aqueous KMnO4 solution) and top‐down sonochemical exfoliation of bulk MnO2 powder. The successful synthesis of δ‐MnO2 nanosheets has been proved through the observation of characteristic Raman peaks at 173 and 634 cm−1 and characteristic X‐ray diffraction peaks. The optical band gap was found to be 1.64 and 1.45 eV for both methods. We also demonstrated that 2D‐MnO2 is a prominent candidate material for ammonia sensing and strain sensing. δ‐MnO2 powder, when employed as cathode material in Li‐ion batteries, results in a stable voltage of ˜0.5 V and in contrast, gives ˜1 V when used in Li‐S batteries and the attained voltage is stable even for >5 h. New methods of synthesis of δ‐MnO2 and its hybrids with graphene will lead to future generation devices, it is expected. [ABSTRACT FROM AUTHOR]

Highlights The electrochemical principles/mechanism of Li–S batteries and origin of the shuttle effect have been discussed. The efficient strategies have been summarized to inhibit the shuttle effect. The recent advances of inhibition of shuttle effect in Li–S batteries for all components from anode to cathode.

[Display omitted] In this work, a new cathode material for lithium–sulfur (Li–S) batteries was developed. Microporous carbon (with predominant pore size £ 1.2 nm) served as both a matrix for sulfur retention and conductive additive. Microporous carbon was shown to be capable of adsorbing lithium polysulfides thereby suppressing their migration toward lithium anode. The discharge capacity of the S/C composite at the 1st and 20th cycles in Li–S battery operation was 513 and 421 mAh g–1 at a scan rate of 0.1 mV s–1. [ABSTRACT FROM AUTHOR]

Abstract δ‐Manganese dioxide (δ‐MnO2) is a 2D material which possesses distinct properties and features due to its unique atomic structure and has already been utilized in numerous disciplines recently, especially in the field of magnetism, energy storage, magnetic resonance imaging, biocatalysts, and fluorescence sensing. Keeping an eye on the huge potential of this 2D material, we report our recent discovery of single‐step synthesis of MnO2 nanosheets via bottom‐up laser crystallization (of aqueous KMnO4 solution) and top‐down sonochemical exfoliation of bulk MnO2 powder. The successful synthesis of δ‐MnO2 nanosheets has been proved through the observation of characteristic Raman peaks at 173 and 634 cm−1 and characteristic X‐ray diffraction peaks. The optical band gap was found to be 1.64 and 1.45 eV for both methods. We also demonstrated that 2D‐MnO2 is a prominent candidate material for ammonia sensing and strain sensing. δ‐MnO2 powder, when employed as cathode material in Li‐ion batteries, results in a stable voltage of ˜0.5 V and in contrast, gives ˜1 V when used in Li‐S batteries and the attained voltage is stable even for >5 h. New methods of synthesis of δ‐MnO2 and its hybrids with graphene will lead to future generation devices, it is expected.

[Display omitted] In this manuscript, nickel/cobalt bimetallic nanocrystals confining into three-dimensional interpenetrating dual-carbon conductive structure (NiCo@C/CNTs) were successfully manufactured by annealing its core-shell structure (Ni-ZIF-67@ZIF-8) precursor under the high temperature. The results presented that the bimetallic nickel and cobalt nanocrystals with superior catalytic activity could quickly convert solid Li 2 S/Li 2 S 2 into soluble LiPSs and effectively decrease the energy barrier. While the hierarchical CNT-porous carbon dual frameworks can provide quick electron/ion transport because of their large specific surface area and the exposure of enough active sites. When used as the separator modifier for lithium sulfur batteries, the battery properties were significantly improved with high specific capacity, outstanding rate capability, and long-term cycle stability. Specifically, its initial specific capacity can achieve to 1038.51 mAh g−1 at 0.5C. At the high rate of 3C, it still delivers satisfactory discharge capacity of 555 mAhg−1 and the capacity decay rate is only 0.065% per cycle after 1000 cycles at 1C. Furthermore, even exposed to heavy sulfur loading (3.61 mg/cm2), they still maintain promising cycle stability. Therefore, such kinds of MOFs derivative with powerful chemical immobilization and catalytic conversion for polysulfides provides a novel guidance for the modification separator and the potential application in the field of high-performance Li-S batteries. [ABSTRACT FROM AUTHOR]

Highlights: The electrochemical principles/mechanism of Li–S batteries and origin of the shuttle effect have been discussed. The efficient strategies have been summarized to inhibit the shuttle effect. The recent advances of inhibition of shuttle effect in Li–S batteries for all components from anode to cathode. Lithium–sulfur (Li–S) batteries are supposed to be one of the most potential next-generation batteries owing to their high theoretical capacity and low cost. Nevertheless, the shuttle effect of firm multi-step two-electron reaction between sulfur and lithium in liquid electrolyte makes the capacity much smaller than the theoretical value. Many methods were proposed for inhibiting the shuttle effect of polysulfide, improving corresponding redox kinetics and enhancing the integral performance of Li–S batteries. Here, we will comprehensively and systematically summarize the strategies for inhibiting the shuttle effect from all components of Li–S batteries. First, the electrochemical principles/mechanism and origin of the shuttle effect are described in detail. Moreover, the efficient strategies, including boosting the sulfur conversion rate of sulfur, confining sulfur or lithium polysulfides (LPS) within cathode host, confining LPS in the shield layer, and preventing LPS from contacting the anode, will be discussed to suppress the shuttle effect. Then, recent advances in inhibition of shuttle effect in cathode, electrolyte, separator, and anode with the aforementioned strategies have been summarized to direct the further design of efficient materials for Li–S batteries. Finally, we present prospects for inhibition of the LPS shuttle and potential development directions in Li–S batteries. [ABSTRACT FROM AUTHOR]

To improve the electrochemical performance of Li‐S batteries, sulfur composites are prepared through sulfur's melt‐diffusion into porous materials such as metal organic frameworks (MOFs). MOFs are porous nanocrystalline materials consisting of metal ions and organic ligands. Due to their high porosity, specific surface area, and easily controllable porous structure, MOFs and their derivatives are considered useful materials for holding sulfur. Herein, the effect of the concentration of the reactants on the particle diameter distribution of ZIF‐67 is studied, and the performance of the product as a sulfur host for Li‐S battery cathode is evaluated. ZIF‐67 was prepared by regulating the Co2+ concentration in solution from 10 to 250 mM, with a constant mole ratio between Co2+ and the organic ligand. Cyclovoltammetry, galvanostatic charge–discharge, and rate capability tests were performed to electrochemically characterize each sample as a sulfur host for Li‐S battery cathodes. MeZ‐50 mM, prepared with 50 mM Co2+ ion solution, had the smallest particle diameter (591 nm). The sulfur cathode utilizing MeZ‐50 mM afforded the best electrochemical performance (883.7 mAh gS−1). This study demonstrates that the particle size of ZIF‐67 can be controlled by adjusting the reactant concentration, enabling manipulation of the electrochemical properties as a sulfur host. [ABSTRACT FROM AUTHOR]

Constructing heterojunctions and hollow multi‐shelled structures can render materials with fascinating physicochemical properties, and have been regarded as two promising strategies to overcome the severe shuttling and sluggish kinetics of polysulfide in lithium–sulfur (Li–S) batteries. However, a single strategy can only take limited effect. Modulating catalytic hosts with synergistic effects are urgently desired. Herein, Mn3O4‐MnS heterogeneous multi‐shelled hollow spheres are meticulously designed by controlled sulfuration of Mn2O3 hollow spheres, and then applied as advanced encapsulation hosts for Li–S batteries. Benefiting from the separated spatial confinement by hollow multi‐shelled structure, ample exposed active sites and built‐in electric field by heterogeneous interface, and synergistic effects between Mn3O4 (strong adsorption) and MnS (fast conversion) components, the assembled battery achieves prominent rate capability and decent cyclability (0.016% decay per cycle at 2 C, 1000 cycles). More crucially, satisfactory areal capacity reaches up to 7.1 mAh cm−2 even with high sulfur loading (8.0 mg cm−2) and lean electrolyte (E/S = 4.0 μL mg−1) conditions. This work will provide inspiration for the rational design of hollow multi‐shelled heterostructure for various electrocatalysis applications. [ABSTRACT FROM AUTHOR]

Abstract Silicon oxide and its derivatives (SiOx, 0

A nitrogen–sulfur dual-doped black fungus porous carbon (NS-FPC) matrix was prepared with natural black fungus as the carbon source and cysteine as the nitrogen–sulfur source. A black fungus-based solution was obtained by hydrothermal treatment. After further carbonization activation and combination with sulfur processing, the NS-FPC/S positive electrode materials were prepared. The uniform recombination of biomass carbon provides an efficient conductive framework for sulfur. The porous structure is conducive to the transport of electrolytes. Heteroatom doping can provide a more active site. The structure and composition analyses of the materials were carried out using X-ray diffraction (XRD). The electronic binding energy and bonding state were analyzed by X-ray photoelectron spectroscopy (XPS). The morphology was observed by scanning electron microscopy and transmission electron microscopy. The specific surface area and pore size distribution were analyzed using an N2 adsorption–desorption experiment. Sulfur loading was determined through thermogravimetric analysis. The electrochemical performance of NS-FPC/S in Li–S batteries was systematically investigated. The result shows that the NS-FPC/S electrode maintains more than 1,000 mAh g-1 reversible capacity after 100 cycles at 0.2 C current density, with a capacity retention of 85%. The cycle and rate performance are both considerably superior to those of traditional activated carbon materials.